Very reliable is reichelt.de who ship worldwide.
Also worldwide shipping is eBay sellerhttps://www.m.ebay.de/sch/i.html?sid=gc ... rue&_pgn=1
Who has good prices and is also very reliable.
And last but not least:if we are talking about a single item I would send you a Z80 free of charge.
Kind regards Paul

In theory, there is no difference between theory and practice. But, in practice, there is.

I need several as I have been borrowing Z80s out of my ZX81s to fix the ones I have refurbished. I have had three dead on arrival zeddies this year and all three had broken Z80s. All the ULAs were fine.

Zilog still make the CMOS versions. They are stocked by Farnell and RS.

You will also find Z80 CPUs on eBay. Both new old stock 2.5MHz Z80 NMOS through to “20MHz” “CMOS” ones. Just keep in mind that some are remarked (being marked as a higher speed than what they were originally labelled as, or being NMOS and not CMOS) but despite this, they should be okay for use in Sinclair computers.

Yeah, the ZX Spectrum (all versions) and the ZX80 / ZX81 / TS1000 / TS1500 etc. all use a Z80 rated at 4MHz (the original Zilog NMOS type number was ‘Z80A’). As far as I know, all of these machines were only ever fitted with 4MHz NMOS Z80 chips.

So yes, a Z80 from a ZX Spectrum should work.

I just want to clarify something I said in my earlier post. The first Z80 CPUs were only rated at 2.5MHz. Officially these are not fast enough to work in Sinclair computers.